June 2000

1

MIC4680

MIC4680

Micrel

MIC4680

1A 200kHz SuperSwitcher™ Buck Regulator

Final Information

General Description

The MIC4680 SuperSwitcher™ is an easy-to-use fixed or

adjustable output voltage step-down (buck) switch-mode

voltage regulator. The 200kHz MIC4680 achieves up to 1.3A

of continuous output current over a wide input range in a

8-lead SOP (small outline package).

The MIC4680 is available in 3.3V and 5V fixed output ver-

sions or adjustable output down to 1.25V.

The MIC4680 has an input voltage range of 4V to 34V, with

excellent line, load, and transient response. The regulator

performs cycle-by-cycle current limiting and thermal shut-

down for protection under fault conditions. In shutdown

mode, the regulator draws less than 2

µA of standby current.

The MIC4680 SuperSwitcher™ regulator requires a mini-

mum number of external components and can operate using

a standard series of inductors and capacitors. Frequency

compensation is provided internally for fast transient re-

sponse and ease of use.

The MIC4680 is available in the 8-lead SOP with a

–40

°C to +125°C junction temperature range.

Typical Applications

SW

L1

68

µH

IN

FB

GND

SHDN

C2

220

µF

16V

D1

B260A or

SS26

3.3V/1A

MIC4680-3.3BM

C1

15

µF

35V

+6V to +34V

SHUTDOWN

ENABLE

5–8

4

3

2

1

Power

SOP-8

Fixed Regulator Circuit

SW

L1

68

µH

IN

FB

GND

SHDN

C2

220

µF

16V

R1

3.01k

R2

2.94k

2.5V/1A

MIC4680BM

C1

15

µF

35V

+5V to +34V

SHUTDOWN

ENABLE

Power

SOP-8

5–8

4

3

2

1

D1

B260A or

SS26

Adjustable Regulator Circuit

Features

• SO-8 package with up to 1.3A output current

• All surface mount solution

• Only 4 external components required

• Fixed 200kHz operation

• 3.3V, 5V, and adjustable output versions

• Internally compensated with fast transient response

• Wide 4V to 34V operating input voltage range

• Less than 2

µA typical shutdown-mode current

• Up to 90% efficiency

• Thermal shutdown

• Overcurrent protection

Applications

• Simple 1A high-efficiency step-down (buck) regulator

• Replacement of TO-220 and TO-263 designs

• Efficient preregulator (5V to 2.5V, 12V to 3.3V, etc.)

• On-card switching regulators

• Positive-to-negative converter (inverting buck-boost)

• Simple battery charger

• Negative boost converter

• Higher output current regulator using external FET

Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com

SuperSwitcher is a trademark of Micrel, Inc.